OT, electrical ? some wood content

Ok, Heres the situation, our front lamp post is out along with garden lights
(hard wired). Found a problem the electrical outlet had been planted
(literally) so it was full of rust and moist dirt. Ok, I removed the bad
outlet replaced it with a weatherproof one mounted off the ground. got 121.6
v at the outlet. I put in NEW bulbs in the lamp post (MADE FROM WOOD) and
nothing. I check
voltage at the post 121.6 put another bulb in nothing, I go back to the
outlet and check voltage, this time its 91.3. I unscrew the bulb and the
voltage goes back to 121.6v. OK, I removed the lamp post head, nothing wrong
up in there, but I cleaned it out and put it back. Still getting 121.6, so I
decided to check the outlet out in a different way, I plugged in my trouble
light and nothing the voltage dropped to 86.3. Unplug the light voltage back
to 121.6.
I'm stuck!
Searcher

A bulb made of Glass and metal seems more useful than a wooden one ;-)

The way you give the Voltage tells me that you are using a digital
voltmeter to measure the voltage; these things have a very high
resistance (at least 10 megohms) and thus do not load the power line
at all: This may result in a voltage that is just coupled in there by
capacitance to be still there, but to drop immediately when loaded.
[...]

It looks as if the cable is broken soewhere between the distribution
box and your outlet. For continued protection against fire and other
hazards you should consider exchanging ist.

Sounds like you still have open wires someplace, even though you
see those voltages. What you measure would depend on what you
measure with and where the bad connections are.
I'm going to guess that you still have something buried that
shouldn't be and you may also be feeding 120V into the ground at
some point. No, that wouldn't pop your breaker, but you would be
paying for power you're not useing, depending on how/where the
short to the soil is made.
You might get something figured out by killing all power to it,
removing all the bulbs, and start making resistance measuerments.
To check for opens, use the 100k or greater scale on your
meter, and to check for shorts, use the lowest scale.
A dead short at some point might still read a few ohms,
depending on the condition of the connections and the length of
the wire being measured.
An open ckt shouldn't register at all on the meter. Anything
measurable means it's not open. Well, assuming you use same
cheap meter most of us can afford, probably from RS.
Sketch it out as you measure, and make notes; it might help
locate it and keep down the amount of digging you have to do.
I'd expect more buried boxes, whatever. Sounds like a kiddie
wired them up.
HTH,
Pop

OK, Thanks for the suggestions, I have cut the power and am currently
checking the lines in the house and as far outside until it goes under
ground. I'll figure this out.
ON the meter, not a RS, its a FLUKE !
Searcher

But what is an "open circuit"? An earlier poster correctly pointed out
that with a high-impedance meter (and RS and Fluke digitals BOTH fall
into this category) you can read a voltage even with an open circuit due
to capacitive coupling between the wires in the cable. Electricians use
a solenoid-type meter that places a small load on the circuit to measure
the voltage. With that type of meter, little or no voltage would be
registered on the meter if the circuit were truly open. So in this case,
the "best" meter is the one suited to the job, and it happens to be the
cheapest one as well.
There is no need to purchase a different instrument, however. It appears
that you have either a broken conductor or a bad connection somewhere.
If you know there are no splices in the line, and the cable is specified
as suitable for burial, I would start to look first at the connections
inside the house and then at the portion of the cable accessible at the
post. Do this with power off, or with extreme caution.
If the cable is not intended for underground use, just replace it. If
you can't locate the problem, replace the cable. Do you know if the lamp
ever worked?
Hope that helps.
Chuck

Sounds like you have some junction corrosion in your wiring
connections. Best way to test it is to set your meter to read ohms.
Turn off the power and with a good piece of wire, [an extension cord
will do] read the resistance from the feeder panel to each socket. Any
resistance over a few ohms indicates a corroded/bad splice/junction.
Bugs

FLUKE is good.
How many wires are here at the outlet? 2, or 3? If 2 (neutral & HOT) I
would suggest replacing the cable entirely with three conductor GREY ROMEX
(Show say it is suitable for burial) and even piping the entire run since
you are going that far.
If there are three conductors, try measuring across both the neutral/hot and
ground (bare conductor)/hot to see if there is any difference.
The suggestion to cut the power and test for a short was a good one. But,
short or not, you don't want to leave that cabling in place, do you?
Is this circuit wired directly back to the breaker box - a "home run" to the
yard lighting? Or, as is so often the case, is the "run" to the yard
lighting tapped off another circuit? Basically, you want to find the start
of the run to the yard lighting and, after removing the connection to the
run, test at that point.

I think what your seeing is voltage drop most likely through a high
resitance connection. Keep checking all the connections that is most
likely where the problem will be. If you can put the bulb in and get
the voltage to drop go back to the source and work your way out to the
first place you get a low reading.
Mike M

It sounds like the Neutral (white) wire is open. Your volt meter is seeing
voltage, but doesn't load the circuit. Any leakage due to dampness, etc.
will provide enough return path for the meter to get a reading. Try checking
the voltage between the black (hot) lead and the green (ground) lead. If the
green wire isn't also broken you should also get 121.6. Instead of a meter
try using a 40 watt or larger light bulb to take your readings. Since the
light bulb draws current and the meter doesn't it will only light if you
truely have a good circuit. In this type of situation a voltmeter can fool
you.

Note: there has been a *LOT* of erroneous information posted in response to
your problem. a 'short', or a 'short to ground' would *not* cause the kind
of problems you're seeing. And, neither the hot or neutral are completely
broken -- if you were getting only the 'capacitative pickup' that others have
proposed, you'd see essentially -zero- volts across the circuit when you
were measuring *with* the light bulb installed.
What you have is a 'reasonably' high resistance in the wiring from the house
to the new outlet.
That resistance is 'as nothing', when the only load on the wiring is your
meter (which has a series-circuit resistance in the mega-ohm range). On the
other hand, the light-bulb has a resistance -- when cold -- that is only
a few ohms (as it heats up to 'white hot', the bulb's resistance increases
radically -- for a 100 watt bulb, it stabilizes at about 83.33333 ohms.)
If the 'cold' resistance is 5% of the 'hot' value, that's only a bit over 4
ohms for a 100 watt bulb. or about 10 ohms, for a 40 watt one.
[ It is worth noting that it doesn't take much resistance to be enough to
provoke a serious voltage drop, even with a load as small as, say, a 40
watt bulb. a whopping 5 ohms of resistance will drop the voltage for a
40 watt bulb by 1/3. circa 40 volt drop across the wire, and 80 volts
across the bulb. BTW, resistance for a 'good' copper wire (16 gauge),
is around 4.7 ohms per thousand feet. for 'bad' wire, it's anybody's
guess. <wry grin> ]
You're seeing the 'way low' voltage, measured across the light-bulb, because
the 'excess' resistance in the wiring is causing a large voltage drop
across the wiring itself. _why_ that excess resistance is there gets
you one step closer to the source of the problem. some possibilities:
1) the wire is 'cracked', somewhere en route. Not entirely broken, but
almost so.
2) there is still crud and contamination at a point where the wire
joins 'something else' -- a prime suspect is at the back of the
outlet, itself.
3) the wire in question is _stranded_ wire (eek!), and water/crud/etc
has gone down the end of the wire, and you have stuff -between- the
strands of the wire. (this has the side-effect of making 'not good'
contact with the screws on the back of the outlet.)
What the "precise" cause is, doesn't really matter. Anything _except_
'dirty contact' at the ends where it ties to something else (the outlet,
or the controlling switch, or the house 'neutral') means that the wire
is _bad_, and the cure for that is "replace it".
Try some soldering flux to de-crud the end of the wire where it connects
to the outlet. If that doesn't fix things, replace the *entire* run
of wire. use something rated for 'direct burial', *and* put it in pipe
of some sort -- the 'direct burial' cable is so that it doesn't just
disintegrate from weather, etc. The pipe is to prevent some idjit with
a shovel (or a powered equivalent) from damaging it. I don't necessarily
mean _you_ are an idiot, but think about the *next* owner. <grin>
Note: there is apparently some other 'funny business' going on -- at 80-90
volts across the light-bulb, you _should_ be seeing *some* 'glow' from the
bulb, although not necessarily a whole lot. Since you're not, this
suggests a 'strangled' (for want of a better word) waveform, that is only
conducting for a small portion of the cycle. how _that_ could be occurring,
other than a misbehaving 'dimmer' on the circuit, I wouldn't even care
to speculate about. If there was a break, with capacitative coupling,
it'd take a *big* capacitative effect to maintain the voltage with the
'poor quality' short (that 4 ohm light-bulb) as a load. (Doing it with
_only_ the voltmeter is no big trick, but doing it 'under load' is something
*very* different.)

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